August 2012
Intermediate to advanced
624 pages
17h 11m
Polish
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17.20. Dodawanie prefiksu lub sufiksu do danych wynikowych
Problem
Chcemy dodać prefiks lub sufiks do każdego wiersza danych wynikowych polecenia. Jako przykład możemy rozważyć sytuację, w której gromadzimy statystyki logowania (last) z wielu komputerów i chcemy ułatwić sobie procedurę wyszukiwania odpowiednich pozycji za pomocą polecenia grep przez dodanie do każdego wpisu informacji o nazwie jednostki.
Rozwiązanie
Należy przekazać dane do pętli while read i polecenia printf. Poniższe instrukcje powodują wyświetlenie nazwy jednostki ($HOSTNAME), za którą występuje znak tabulatora oraz niepusty wiersz listingu wynikowego instrukcji last.
$ last | while read i; do [[ -n "$i" ]] && printf "%b" "$HOSTNAME\t$i\n"; done # Zapis nowego pliku dziennika $ ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.